Potassium Citrate for Diabetes Insipidus

INDICATIONS AND USAGE Potassium Citrate Extended-Release Tablets are a citrate salt of potassium indicated for the management of: • Renal tubular acidosis (RTA) with calcium stones ( 1.1 ) • Hypocitraturic calcium oxalate nephrolithiasis of any etiology ( 1.2 ) • Uric acid lithiasis with or without calcium stones ( 1.3 ) 1.1 Renal Tubular Acidosis (RTA) with Calcium Stones Potassium citrate is indicated for the management of renal tubular acidosis [see Clinical Studies ( 14.1 )] . 1.2 Hypocitraturic Calcium Oxalate Nephrolithiasis of any Etiology Potassium citrate is indicated for the management of hypocitraturic calcium oxalate nephrolithiasis [see Clinical Studies ( 14.2 )] . 1.3 Uric Acid Lithiasis with or without Calcium Stones Potassium citrate is indicated for the management of uric acid lithiasis with or without calcium stones [see Clinical Studies ( 14.3 )] .

DOSAGE AND ADMINISTRATION Objective: To restore normal urinary citrate (greater than 320 mg/day and as close to the normal mean of 640 mg/day as possible), and to increase urinary pH to a level of 6.0 to 7.0. Severe hypocitraturia (urinary citrate < 150 mg/day): therapy should be initiated at 60 mEq per day; a dose of 30 mEq two times per day or 20 mEq three times per day with meals or within 30 minutes after meals or bedtime snack ( 2.2 ) Mild to moderate hypocitraturia (urinary citrate > 150 mg/day): therapy should be initiated at 30 mEq per day; a dose of 15 mEq two times per day or 10 mEq three times per day with meals or within 30 minutes after meals or bedtime snack ( 2.3 ) 2.1 Dosing Instructions Treatment with extended release potassium citrate should be added to a regimen that limits salt intake (avoidance of foods with high salt content and of added salt at the table) and encourages high fluid intake (urine volume should be at least two liters per day). The objective of treatment with Potassium Citrate extended-release tablets is to provide Potassium Citrate extended-release tablets in sufficient dosage to restore normal urinary citrate (greater than 320 mg/day and as close to the normal mean of 640 mg/day as possible), and to increase urinary pH to a level of 6.0 or 7.0. Monitor serum electrolytes (sodium, potassium, chloride and carbon dioxide), serum creatinine and complete blood counts every four months and more frequently in patients with cardiac disease, renal disease or acidosis. Perform electrocardiograms periodically. Treatment should be discontinued if there is hyperkalemia, a significant rise in serum creatinine or a significant fall in blood hematocrit or hemoglobin. 2.2 Severe Hypocitraturia In patients with severe hypocitraturia (urinary citrate < 150 mg/day), therapy should be initiated at a dosage of 60 mEq/day (30 mEq two times/day or 20 mEq three times/day with meals or within 30 minutes after meals or bedtime snack). Twenty-four hour urinary citrate and/or urinary pH measurements should be used to determine the adequacy of the initial dosage and to evaluate the effectiveness of any dosage change. In addition, urinary citrate and/or pH should be measured every four months. Doses of Potassium Citrate extended-release tablets greater than 100 mEq/day have not been studied and should be avoided. 2.3 Mild to Moderate Hypocitraturia In patients with mild to moderate hypocitraturia (urinary citrate > 150 mg/day) therapy should be initiated at 30 mEq/day (15 mEq two times/day or 10 mEq three times/day with meals or within 30 minutes after meals or bedtime snack). Twenty-four hour urinary citrate and/or urinary pH measurements should be used to determine the adequacy of the initial dosage and to evaluate the effectiveness of any dosage change. Doses of Potassium Citrate extended-release tablets greater than 100 mEq/day have not been studied and should be avoided.

WARNINGS AND PRECAUTIONS Hyperkalemia: In patients with impaired mechanisms for excreting potassium, potassium citrate extended-release tablets administration can produce hyperkalemia and cardiac arrest. Potentially fatal hyperkalemia can develop rapidly and be asymptomatic. The use of potassium citrate extended-release tablets in patients with chronic renal failure, or any other condition which impairs potassium excretion such as severe myocardial damage or heart failure, should be avoided ( 5.1 ) Gastrointestinal lesions: if there is severe vomiting, abdominal pain or gastrointestinal bleeding, potassium citrate extended-release tablets should be discontinued immediately and the possibility of bowel perforation or obstruction investigated ( 5.2 ) 5.1 Hyperkalemia In patients with impaired mechanisms for excreting potassium, potassium citrate extended-release tablets administration can produce hyperkalemia and cardiac arrest. Potentially fatal hyperkalemia can develop rapidly and be asymptomatic. The use of potassium citrate extended-release tablets in patients with chronic renal failure, or any other condition which impairs potassium excretion such as severe myocardial damage or heart failure, should be avoided. Closely monitor for signs of hyperkalemia with periodic blood tests and ECGs. 5.2 Gastrointestinal Lesions Because of reports of upper gastrointestinal mucosal lesions following administration of potassium chloride (wax-matrix), an endoscopic examination of the upper gastrointestinal mucosa was performed in 30 normal volunteers after they had taken glycopyrrolate 2 mg p.o. t.i.d., potassium citrate extended-release tablets 95 mEq/day, wax-matrix potassium chloride 96 mEq/day or wax-matrix placebo, in thrice daily schedule in the fasting state for one week. Potassium citrate extended-release tablets and the wax-matrix formulation of potassium chloride were indistinguishable but both were significantly more irritating than the wax-matrix placebo. In a subsequent, similar study, lesions were less severe when glycopyrrolate was omitted. Solid dosage forms of potassium chlorides have produced stenotic and/or ulcerative lesions of the small bowel and deaths. These lesions are caused by a high local concentration of potassium ions in the region of the dissolving tablets, which injured the bowel. In addition, perhaps because wax-matrix preparations are not enteric-coated and release some of their potassium content in the stomach, there have been reports of upper gastrointestinal bleeding associated with these products. The frequency of gastrointestinal lesions with wax-matrix potassium chloride products is estimated at one per 100,000 patient-years. Experience with potassium citrate extended-release tablets is limited, but a similar frequency of gastrointestinal lesions should be anticipated. If there is severe vomiting, abdominal pain or gastrointestinal bleeding, potassium citrate extended-release tablets should be discontinued immediately and the possibility of bowel perforation or obstruction investigated.

DRUG INTERACTIONS The following drug interactions may occur with potassium citrate: Potassium-sparing diuretics: concomitant administration should be avoided since the simultaneous administration of these agents can produce severe hyperkalemia (7.1) Drugs that slow gastrointestinal transit time: These agents (such as anticholinergics) can be expected to increase the gastrointestinal irritation produced by potassium salts (7.2) Renin-angiotensin-aldosterone inhibitors: Monitor for hyperkalemia (7.3) Nonsteroidal Anti-inflammatory drugs (NSAIDs) monitor for hyperkalemia (7.4) 7.1 Potential Effects of Potassium citrate on Other Drugs Potassium-sparing Diuretics: Concomitant administration of potassium citrate extended-release tablets and a potassium-sparing diuretic (such as triamterene, spironolactone or amiloride) should be avoided since the simultaneous administration of these agents can produce severe hyperkalemia. 7.2 Potential Effects of Other Drugs on Potassium citrate Drugs that slow gastrointestinal transit time: These agents (such as anticholinergics) can be expected to increase the gastrointestinal irritation produced by potassium salts. 7.3 Renin-Angiotensin-Aldosterone System Inhibitors 7.3 Renin-Angiotensin-Aldosterone System Inhibitors Drugs that inhibit the renin-angiotensin-aldosterone system (RAAS) including angiotensin converting enzyme (ACE) inhibitors, angiotensin receptor blockers (ARBs), spironolactone, eplerenone, or aliskiren produce potassium retention by inhibiting aldosterone production. Closely monitor potassium in patients receiving concomitant RAAS therapy. 7.4 Nonsteroidal Anti-Inflammatory Drugs (NSAIDs) NSAIDs may produce potassium retention by reducing renal synthesis of prostagladin E and impairing the renin-angiotensin system. Closely monitor potassium in patients on concomitant NSAIDs.

ADVERSE REACTIONS Some patients may develop minor gastrointestinal complaints such as abdominal discomfort, vomiting, diarrhea, loose bowel movements or nausea. These may be alleviated by taking the dose with meals or snacks or by reducing the dosage ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Upsher-Smith Laboratories, LLC at 1-855-899-9180 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.1 Postmarketing Experience Some patients may develop minor gastrointestinal complaints during potassium citrate extended-release tablets therapy, such as abdominal discomfort, vomiting, diarrhea, loose bowel movements or nausea. These symptoms are due to the irritation of the gastrointestinal tract, and may be alleviated by taking the dose with meals or snacks, or by reducing the dosage. Patients may find intact matrices in their feces.